The Brazilian researchers found that women experienced a significant boost to their arousal and sexual satisfaction following the procedure. However, they also noted that women who experienced stretch marks as a result of their breast implants did not experience any improvement in their sex lives.

Experts sharply disagreed on the sexual and psychological benefits of breast implants.

"I think that the female breast is a very important part of a woman's body, in terms of how a woman feels about herself in public, how her clothes fit and how she feels about herself sexually," said Dr. David Reath, chair of the public education committee of the American Society of Plastic Surgeons (ASPS). "It's very common for a woman post-surgery to say she feels more confident, that her outward body now fits her inward persona."

However, there could be other reasons behind the women's reports of enhanced sex lives, said Tomi-Ann Roberts, a distinguished professor of psychology at Colorado College and a member of the American Psychological Association's task force on the sexualization of girls.

"When we have exerted a great effort, spent a great deal of money and effort and time on something, we tend to justify that effort," Roberts said. "Our good feeling is increased because of the effort, not the thing itself."

Researcher Dr. Paulo Guimaraes and colleagues asked the women to fill out a questionnaire before the surgery that assessed their sexual desire, arousal and sexual satisfaction. Patients were then asked to retake the questionnaire at two, four and 18 months after surgery.

The 36 women who did not develop postsurgical stretch marks said they had experienced improved levels of arousal and were more satisfied with their sex lives, researchers said. They reported this improvement at both four and 18 months following surgery.

"They found that in the areas of both sexual satisfaction and sexual arousal, there were significantly increased feelings," Reath said. "These aspects of the sexual experience were increased for these women."

Nine women with stretch marks following their plastic surgery did not report any improvement. Stretch marks can occur if the implant is significantly larger than the original breast was, according to the ASPS.

The findings are to be presented this week at the ASPS annual meeting in San Diego. The data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.

Reath said he wasn't surprised by the findings.

"When I see patients and follow up, a lot of them will say 'My husband and I or my boyfriend and I are having a lot of fun.' Why not? It's an important part of life," he said.

Roberts also was not surprised, but for different reasons.

"Here are 45 women who spent a great deal of time and money and effort augmenting their breasts because the media has clearly convinced them their breasts are inadequate, so we shouldn't be surprised they are pleased with the breast augmentation," she said.

"We further shouldn't be surprised that they are pleased in the arena of their sexuality," Roberts continued. "Feminine heterosexuality is very much about our sense of whether or not we are pleasing our partner, and here we have 45 women who have spent a great deal of money to that purpose. If these breasts are now pleasing to their male partners, then they are likely to feel more sexually attractive."

She said the study might have been more interesting had it also included some more practical questions related to their new breasts -- for example, related to their ability to breast-feed or their comfort while jogging.

"There are a lot of other things breasts are a part of. This is an indication that in our Victoria's Secret culture, breasts are for men. They are for men's pleasure," she said.